package com.lzh.java1;

/**
 * @author liuzhihao
 * @create 2021-02-13 19:44
 */

/**
 * 使用同步机制将单例模式中的懒汉式改写为线程安全的
 *
 *
 */
public class BankTest {
}
class Bank{

    private Bank(){

    }

    private static Bank instance = null;

    public static Bank getInstance(){
        //方式一：效率稍差
//        synchronized (Bank.class) {
//            if(instance == null){
//                instance = new Bank();
//            }
//            return instance;
//        }
        //方式二:效率更高
        if(instance == null){
            synchronized (Bank.class) {
                if(instance == null){
                    instance = new Bank();
                }
            }
        }
        return instance;
    }
}